1. Field of the Invention
This invention relates to a conveying system for a mining machine, and more particularly, to a cascading arrangement of conveyors extending rearwardly on the mining machine frame where a fixed conveyor transfers dislodged material to an end conveyor pivotally mounted on a ground engaging stabilizer of the machine frame for lateral swinging movement to provide increased maneuverability of the mining machine in the mine.
2. Description of the Prior Art
In underground mining operations, it is a well known practice to dislodge solid material from the mine face by a mining machine and convey the material rearwardly on a main conveyor that extends longitudinally on the mining machine. A discharging conveyor section is connected to the main conveyor to pivot relative thereto about a fixed vertical axis. The mined material may be transferred from the discharging conveyor section in one mode to a track haulage system or a belt-type haulage unit or in another mode to a shuttle car which shuttles back and forth from the working face to a fixed discharge station where the mined material is conveyed to the surface.
The pivotal conveyor discharging section is intended to permit the mining machine to maneuver in a crosscut and along a curved path without extended interruption of the mining operation to remove the mined material from the working face. A number of solutions have been proposed to the problem of maintaining substantially continuous rearward movement of the mined material on the mining machine conveyor without interrupting the mining operation. One approach to increasing the maneuverability of the mining machine is the use of articulated conveying sections and cascading arrangements of conveyors with the mining machine, as disclosed in U.S. Pat. No. 4,387,798.
U.S. Pat. No. 2,613,800 discloses an example of an articulated conveyor for a loading machine which gathers the mined material and loads it onto a conveyor mechanism. The conveyor mechanism includes a forward trough section supported by a frame and connected to a delivery section which extends rearwardly through a pivotal connection. The delivery section is swung laterally by piston cylinder assemblies. The forward trough section is movable vertically by a piston cylinder assembly. A centrally disposed endless chain drives flights from the forward section across the pivotal connection to the delivery section.
U.S. Pat. No. 2,722,409 discloses an articulated cascading conveyor which receives mined material from the rearward end of a continuous mining machine. The cascading conveyor transfers the material onto another cascading conveyor and therefrom to successive intermediate cascading sections onto another belt conveyor.
U.S. Pat. No. 3,268,058 discloses a self-propelled sinuous conveyor comprising a series of interconnected discrete units which are self-steerable and guided by an electrical guidance system along a lead wire. The conveyor receives material from a continuous mining machine and conveys it rearwardly along the discrete units by a series of cascading conveyor belts.
U.S. Pat. No. 3,993,204 discloses an extensible conveyor comprising telescoping boom sections connected by piston cylinder assemblies. A chain extends around the periphery of the boom sections in a horizontal plane and is wound at its distal end around a vertically journaled sprocket wheel and a series of aligned idler sprockets at the proximal end thereof. A row of idler sprockets on a slide bar adjacent the proximal end of the conveyor take-up slack in the chain as the conveyor is extended and retracted.
Further examples of articulated conveyor assemblies for mining machinery are disclosed in U.S. Pat. Nos. 3,557,937; 4,089,403; and 4,281,879. Each of these conveyor assemblies includes a fixed section on a frame of a mining machine and a swingable section extending rearwardly therefrom and pivotally connected thereto. A pivot or swivel assembly connects the fixed section with the swingable section.
U.S. Pat. No. 4,089,403 discloses a link with a pivot point for a swingable conveyor section vertically aligned with another pivot point for a fixed conveyor section on a mining machine. The pivot points also have arcuate end sections with intermeshing gears such that a piston cylinder assembly rotating the link relative to the frame of the mining machine rotates the swingable section twice the degree of rotation of the link. With this arrangement, the swingable section is capable of pivoting or swinging laterally through an expanded arc.
U.S. Pat. No. 4,090,601 discloses a conveyor with a fixed section on the frame of a mining machine and a laterally swingable section pivotally extending therefrom. A take-up cylinder operates at a pressure proportional to the fluid pressure supply to the drive side of the conveyor drive motor to take-up slack in the endless chain of the conveyor as it swings laterally around the pivot connection relative to the mining machine frame. The drive to the conveyor is transmitted through the discharge end thereof, which is mounted in the frame of the conveyor for longitudinal movement by the take-up cylinder to adjust tension on the conveyor and eliminate slack in the conveyor when pivoted laterally.
There is need for conveying apparatus on a mining machine that facilitates maneuvering the mining machine as it dislodges material from the mine face so that the mined material is substantially continuously transported from the mine face without encountering delays due to the inability to maintain a continuous conveying surface. While it is known to utilize cascading-type conveyor units for transporting material rearwardly of a mining machine and mining machines having laterally swingable sections pivotally connected to fixed sections, the prior art systems provide a limited range of pivotal movement that restricts the maneuverability of the mining machine or require a multiplicity of connected, articulated conveying sections to provide a curved conveying path.